During some births it becomes necessary to monitor the fetal heart rate. A fetal electrode, such as the one illustrated in U.S. Pat. No. 3,827,428, is attached to the scalp of the fetus and a pair of leads is passed back through the birth canal to a connector strapped to the mother's leg, hence these connectors are usually referred to as “leg-plate” connectors. An additional electrode from the leg-plate connector is attached to the mother to establish a base or reference potential for the electrical signals of the fetal electrode. The electrical signals from the fetal electrode and the reference electrode are then fed to a fetal monitor via leads extending from the leg-plate connector.
Examples of conventional leg-plate connectors are illustrated in U.S. Pat. No. 5,199,432, U.S. Pat. No. 6,321,103, U.S. Pat. No. 6,363,272 and US-A-2005137486. In these arrangements, the leg-plate connector can be re-used. They are provided with a socket for receiving an elongate plug attached to the ends of the electrode wires. Due to the presence of bodily fluids, however, there is a significant health risk of cross-contamination, for example, where leg-plate connectors are not adequately cleaned and sterilised before they are reused. Many developments have been made to try to minimise the ingress of bodily fluids and to resist the aggressive antiseptic detergents, for example the inclusion of O-ring seals and the use of special materials, but these have also lead to complicated manufacturing processes and high production costs.
As a result, moves have been made to develop single-use, disposable, leg-plate connectors, which can benefit from a more simplified construction and reduced cost. Examples are shown in U.S. Pat. No. 4,209,020, U.S. Pat. No. 5,062,426, U.S. Pat. No. 5,197,472 and U.S. Pat. No. 5,404,876. One recognised advantage of disposable leg-plate connectors is that they can be made lighter and have a lower profile, and this leads to improved comfort for the wearer and improvements to the quality of the fetal ECG signal. In order to make these disposable leg-plate connectors as thin as possible, the wires from the fetal electrode were fed individually as bare wires into a terminal, in order to make an electrical contact. The use of such bare wires is no longer allowed for leg-plate connectors.
A problem with these thin, single-use, leg-plate connectors is that while they offer some advantages, they have not been optimised for use by the person fitting the device, e.g., the midwife. The flexible electrode wires are small and can be difficult to connect up, particularly in the presence of bodily fluids. It is paramount that a good connection is made with the ends of the fetal electrode leads, otherwise there is a reduction in the signal quality. It is also important to obtain a good signal from the material reference electrode positioned under the connector.
It would also be desirable to provide a method of manufacturing such a connector that is straight forward and low cost.
There is also a problem that the current single-use connector systems do not prevent re-use.